Conductive powder formation method, device for forming conductive powder, and method of forming semiconductor device

ABSTRACT

A method of forming a conductive powder includes reducing, by a reduction reaction, a conductive powder precursor gas using a plasma. Reducing the conductive powder precursor gas forms the conductive powder. The method further includes filtering the conductive powder based on particle size. The method further includes dispersing a portion of the conductive powder having a particle size below a threshold value in a fluid.

BACKGROUND

In semiconductor technology, interconnects are formed on a substrate toelectrically connect various active components of a semiconductordevice. The interconnects are formed as conductive lines, which extendsubstantially parallel to a top surface of the substrate, and conductivevias, which electrically connect conductive lines on different metallayers. A metal layer is a group of conductive lines having a samedistance from the top surface of the substrate. A group of conductivelines closest to the substrate is often called metal layer zero (M0).

Conductive lines are formed by creating openings in a dielectricmaterial and filling those openings with a conductive material. Aplanarization process is used to remove excess conductive materialfollowing filling of the openings. As critical dimensions ofsemiconductor devices continue to shrink, filling the openings becomesmore challenging.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a flowchart of a method of forming a conductive powder inaccordance with some embodiments.

FIG. 2 is a schematic diagram of a device for forming a conductivepowder in accordance with some embodiments.

FIG. 3 is a flowchart of a method of forming a semiconductor device inaccordance with some embodiments.

FIGS. 4A, 4B, 4C and 4D are cross-sectional views of a semiconductordevice at various stages of manufacture in accordance with someembodiments.

FIG. 5 is a schematic view of a controller for controlling a device forforming a conductive powder in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components, values, operations, materials,arrangements, or the like, are described below to simplify the presentdisclosure. These are, of course, merely examples and are not intendedto be limiting. Other components, values, operations, materials,arrangements, or the like, are contemplated. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

As technology nodes decrease, effectively filling openings or conductivelines and vias becomes more difficult. Approaches such as sputtering orplating create voids in the conductive lines or vias, in some instances.In addition, approaches like plating increase a carbon content in theconductive lines or vias, in some instances. Voids and increased carboncontent reduce reliability of the conductive lines and vias to performas intended. Filling openings using conductive powders helps to reduce acarbon content in the conductive lines or vias. However, conductivepowders having a particle size which is too large in comparison with asize of the openings reduces reliability in effectively filling theopenings. By forming a conductive powder which has a small particle sizeand filling openings for conductive lines or vias in a semiconductordevice with the conductive powder, reliability of the semiconductordevice and production yield are increased.

FIG. 1 is a flow chart of a method 100 of forming a conductive powderaccording to some embodiments. Method 100 is able to form a conductivepowder having an average particle diameter ranging from about 1nanometer (nm) to about 5 microns (μm). Other approaches for forming aconductive powder which has an average particle diameter of greater than5 μm are not able to reliably fill openings in dielectric layers atadvanced technology nodes, in some instances. As a particle sizeincreases, a risk of voids forming when filling an opening forconductive lines using a conductive powder increases. Voids increaseresistance within the conductive line. The increased resistance reducesprecision of signal transfer and increases power consumption of thesemiconductor device. As critical dimensions for semiconductor devicesdecreases, a smaller particle size helps to fill openings forinterconnects more reliably to reduce occurrence of voids in theconductive lines.

In operation 102, a conductive powder precursor gas is preheated. Theconductive powder precursor gas is preheated to a temperature below adecomposition temperature of the conductive powder precursor gas. Insome embodiments, the conductive powder precursor gas is heated to atemperature ranging from about 100° C. to about 600° C. If thetemperature of the preheated conductive powder precursor gas is too low,reaction times for forming the conductive powder are increased and yieldof the conductive powder production process is decreased, in someinstances. If the temperature of the preheated conductive powderprecursor gas is too high, a risk of decomposition of the preheatedconductive powder precursor gas increases and yield of the conductivepowder production process decreases, in some instances.

A material of the conductive powder precursor gas depends on a materialof a conductive powder to be formed by method 100. In some embodiments,the conductive powder to be formed by method 100 includes aluminum,cobalt, copper, gold, magnesium, nickel, silver, titanium, zinc, alloysthereof or other suitable conductive material. In some embodiments, theconductive powder precursor gas includes a conductive-material organiccompound. The conductive-material organic compound includes the materialof the conductive powder to be formed by method 100 bonded to at leastone methyl group. For example, in some embodiments where the conductivepowder to be formed by method 100 is aluminum, the conductive powderprecursor gas includes Al₂(CH₃)₆. In some embodiments, the conductivepowder precursor gas includes a conductive-material halide compound. Theconductive-material halide compound includes at least one halogenmaterial bonded to the material of the conductive powder to be formed bymethod 100. For example, in some embodiments, where the conductivepowder to be formed by method 100 is aluminum, the conductive powderprecursor gas includes AlCl₃. In some embodiments, the conductive powderprecursor gas includes more than one compound including a sameconductive powder material, for example Al₂(CH₃)₆ and AlCl₃ are bothincluded as part of the conductive powder precursor gas. In someembodiments, the conductive powder precursor gas includes compounds forforming conductive powders having different materials, for exampleAl₂(CH₃)₆ and CuCl₂ are both included as part of the conductive powderprecursor gas.

In some embodiments, the conductive powder precursor gas is preheatedprior to entering a reaction chamber. In some embodiments, theconductive powder precursor gas is preheated in a portion of thereaction chamber prior to interacting with other materials inside thereaction chamber. In some embodiments, the conductive powder precursorgas is formed by atomizing a liquid using an ejection process. In someembodiments, the conductive powder precursor gas is formed by vaporizinga liquid by heating the liquid.

In operation 104, the preheated conductive powder gas passes through aplasma heating zone. The plasma heating zone includes a plasma having amixture of a hydrogen plasma and an inert gas plasma. In someembodiments, the inert gas for forming the inert gas plasma includesnitrogen gas, argon, helium or another suitable inert gas. The plasma isignited prior to interacting with the preheated conductive powderprecursor gas. The plasma reacts with the preheated conductive powdergas to remove the organic material or halide material from theconductive powder. The hydrogen plasma within the plasma mixture helpsto prevent oxidation of the conductive powder material by reducing,i.e., by a reduction reaction, the conductive powder material.

In some embodiments, the hydrogen and the inert gas enter the reactionchamber by separate input ports. In some embodiments, the hydrogen andthe inert gas enter the reaction chamber by a same input port. In someembodiments, a pressure in the reaction chamber during the reaction ofthe preheated conductive powder precursor gas ranges from about 10milliTorr (mTorr) to about 20 Torr. The pressure in the reaction chamberhelps to determine an amount of reactant materials within the reactionchamber to help control a rate of reaction. A radio frequency (RF) powerapplied in the reaction chamber depends on a volume of the reactionchamber. As the volume of the reaction chamber increases, the RF powerapplied in the reaction chamber also increases. In some embodiments, theRF power applied in the reaction chamber ranges from about 10 watts (W)to about 300 kilowatts (kW). The RF power applied helps to ignite theplasma for the plasma mixture. A temperature of the reaction chamberranges from about 100° C. to about 600° C. The temperature of thereaction chamber is below the decomposition temperature of theconductive powder precursor gas. In some embodiments, the reactionchamber temperature is equal to the temperature of the preheatedconductive powder precursor gas. In some embodiments, the temperature ofthe reaction chamber is greater than the temperature of the preheatedconductive powder precursor gas.

The reaction between plasma and the preheated conductive powderprecursor gas forms a conductive powder. In some embodiments, using thereaction between the plasma and the preheated conductive powderprecursor gas produces a particle distribution where about 95% of theparticles have a diameter equal to or less than 5 nm; and about 5% ofthe particles have a diameter greater than 5 nm.

In operation 106, an ultrasonic vibration is performed on the reactionchamber. The ultrasonic vibration helps to prevent the conductive powderor by-products from adhering and building up on walls of the reactionchamber. The walls of the reaction chamber are coated with graphene toreduce friction between the walls of the reaction chamber and theconductive powder and by-products to help reduce build up on thereaction chamber walls. The combination of the graphene coating and theultrasonic vibration helps to prolong maintenance cycles for thereaction chamber in order to increase productivity of method 100.

In some embodiments, the ultrasonic vibration is produced by a vibrationgenerator. In some embodiments, the vibration generator includestransducers on an outer surface of the reaction chamber. In someembodiments, the vibration generator includes a gas flowing through achannel or rotating a bearing within a chamber. In some embodiments,operation 106 is performed simultaneously with operation 104.

In operation 108, the conductive powder is collected. The conductivepowder is charged because of the plasma reaction. In some embodiments,the conductive powder is collected using an electro-static collector(ESC) to direct the conductive powder into at least one collection cell.In some embodiments, multiple collection cells are arranged parallelwith each other. In some embodiments, the ESC is used to help separatethe conductive powder based on particle size into different collectioncells. As a particle size decreases, the ESC is able to move theconductive powder a greater distance in order to separate the conductivepowder into different collection cells. In some embodiments, theconductive powder is collected using a vacuum pump to pull theconductive powder into a collection chamber.

In operation 110, the conductive powder is filtered. The conductivepowder is filtered based on particle size. In some embodiments, asdiscussed above, the collection process helps to filter the conductivepowder. In some embodiments, the collection process and the filteringprocess are performed simultaneously. In some embodiments, a separatefiltering process is performed after the collection process.

In some embodiments, the conductive powder is filtered using acentrifugal process. The conductive powder is dispersed in a solvent toform a mixture. The solvent is free of oxygen in order to reduce therisk of oxidation of the conductive powder. In some embodiments, thesolvent includes methane, acetone, isopropyl alcohol or another suitablesolvent material. The mixture is placed in a centrifuge in order toseparate the particles of the conductive powder based on weight. Since acomposition of the particles of the conductive powder is substantiallyuniform amongst the particles, the weight-based separation provided bythe centrifugal process is a size-based separation.

In some embodiments, a combination of filtering techniques is used toseparate particles of the conductive powder. For example, in someembodiments, both an ESC filtering process and a centrifugal process areused. In some embodiments, a filtering process is repeated. For example,in some embodiments, the centrifugal process is repeated at least twicein order to provide a more precise filtering of particles of theconductive powder.

In operation 112, the conductive powder is dispersed in a fluid. In someembodiments, operation 112 is combined with operation 110 and the fluidis the solvent. In some embodiments, operation 112 is performedsequentially with operation 110. In some embodiments, the fluid isdifferent from the solvent. In some embodiments, the fluid is a samematerial as the solvent. The fluid has a low metal oxidation rate. Insome embodiments, the fluid includes methane, acetone, isopropylalcohol, acetone, ethyl acetate or another suitable fluid. In someembodiments, an emulsifying agent is included in the fluid. In someembodiments, the emulsifying agent is omitted. The fluid is used tosuspend the conductive powder to assist with application of theconductive powder to a semiconductor device. In some embodiments, adifferent fluid is used for different size particles of the conductivepowder. For example, in some embodiments, a smallest size of particlesfollowing operation 110 is dispersed in a first fluid while a largersize of particles is dispersed in a second fluid different from thefirst fluid.

The fluid is directed into a container storing the conductive powder ata sufficiently low flow rate to prevent scattering of the particles ofthe conductive powder. As the size of the particles of the conductivepowder decreases, the flow rate of the fluid also decreases.

In optional operation 114, the particles of the conductive powder havinga diameter above a threshold value are recycled through method 100. Insome embodiments, the threshold value is 5 μm. In some embodiments, theparticles having the diameter greater than the threshold value areremoved from a solvent by evaporating the solvent. In some embodiments,operation 114 is omitted and particles having a diameter above thethreshold value are directed to a process which has a higher tolerancefor particle size, such as a process for a larger technology node.

In some embodiments, an order of operations of method 100 is altered.For example, in some embodiments, operation 112 occurs before operation110. In some embodiments, at least two operations of method 100 areperformed simultaneously. For example, in some embodiments operation 106is performed simultaneously with operation 104. In some embodiments, atleast one operation of method 100 is omitted. For example, in someembodiments, operation 114 is omitted as discussed above.

FIG. 2 is a schematic diagram of a device 200 for forming a conductivepowder in accordance with some embodiments. Device 200 includes areaction chamber 210. A conductive powder precursor gas input 220; aninert gas input 230; and a hydrogen gas input 240 are connected toseparate ports in reaction chamber 210. An RF power unit 245 isconfigured to ignite a plasma of the inert gas and the hydrogen gas tointeract with the conductive powder precursor gas. A vibration unit 250is attached to an outer surface of reaction chamber 210. A coolingsection 260 is located at an output of reaction chamber 210 in order tocool the conductive powder formed in the reaction chamber. A collector270 is configured to collect the conductive powder exiting reactionchamber 210 after passing through cooling section 260. Powder collectingcells 280 is configured to receive the conductive powder from collector270 and to help separate the conductive powder based on particlediameter. A valve 275 is between collector 270 and powder collectingcells 280 in order selectively permit the conductive powder to transferfrom collector 270 to powder collecting cells 280. A solvent supply line290 is configured to supply a solvent for dispersing the conductivepowder in powder collecting cells 280. A pump 295 is configured to helpremove conductive powder from powder collecting cells 280. A valve 285is between powder collecting cells 280 and each of solvent supply line290 and pump 295 in order to selectively permit solvent to enter powdercollecting cells 280 and selectively permit removal of conductive powderfrom powder collecting cells 280. A controller 297 is configured tocontrol components of device 200 in order to produce the conductivepowder.

Reaction chamber 210 is configured to receive conductive powderprecursor gas from conductive powder precursor gas input 220; inert gasfrom inert gas input 230; and hydrogen gas from hydrogen gas input 240.In some embodiments, reaction chamber 210 includes a region forpreheating the conductive powder precursor gas prior to interaction withthe hydrogen gas or inert gas. In some embodiments, reaction chamber 210includes preheated conductive powder precursor gas. RF power unit 245 isconfigured to ignite the hydrogen gas and the inert gas in order to forma plasma. Reaction chamber 210 is configured to direct the preheatedconductive powder precursor gas to interact with the plasma. The plasmaperforms a reduction reaction with the preheated conductive powderprecursor gas in order to form a conductive powder. In some embodiments,a pressure in reaction chamber 210 during the reaction of the preheatedconductive powder precursor gas ranges from about 10 mTorr to about 20Torr. The pressure in reaction chamber 210 helps to determine an amountof reactant materials within the reaction chamber to help control a rateof reaction. Sidewalls of reaction chamber 210 are coated with graphenein order to reduce adherence of the conductive powder and by-products ofthe reaction on the sidewalls. Vibration unit 250 also helps to reduceadherence of conductive powder and by-products on sidewalls of reactionchamber 210.

Conductive powder precursor gas input 220 is configured to conveyconductive powder precursor gas from a supply to reaction chamber 210.In some embodiments, the conductive powder to be formed using device 200includes aluminum, cobalt, copper, gold, magnesium, nickel, silver,titanium, zinc, alloys thereof or other suitable conductive material. Insome embodiments, the conductive powder precursor gas includes aconductive-material organic compound. In some embodiments, theconductive powder precursor gas includes a conductive-material halidecompound. In some embodiments, a heater is connected to conductivepowder precursor gas input 220 in order to preheat the conductive powderprecursor gas. In some embodiments, the heater includes a heatexchanger, an electric heater or another suitable heater. The conductivepowder precursor gas is preheated to a temperature below a decompositiontemperature of the conductive powder precursor gas. In some embodiments,the conductive powder precursor gas is heated to a temperature rangingfrom about 100° C. to about 600° C. Conductive powder precursor gasinput 220 is connected to a separate port in reaction chamber 210 frominert gas input 230 and hydrogen gas input 240. In some embodiments,conductive powder precursor gas input 220 is connected to a same port inreaction chamber 210 as at least one of inert gas input 230 or hydrogengas input 240.

Inert gas input 230 is configured to provide an inert gas from an inertgas supply to reaction chamber 210. In some embodiments, the inert gasfor forming the inert gas plasma includes nitrogen gas, argon, helium oranother suitable inert gas. Inert gas input 230 is connected to aseparate port of reaction chamber 210 from conductive powder precursorgas input 220 and hydrogen gas input 240. In some embodiments, inert gasinput 230 shares a port of reaction chamber 210 with at least one ofconductive powder precursor gas input 220 or hydrogen gas input 240.

Hydrogen gas input 240 is configured to provide hydrogen gas from ahydrogen gas supply to reaction chamber 210. Hydrogen gas input 240 isconnected to a separate port of reaction chamber 210 from conductivepowder precursor gas input 220 and inert gas input 230. In someembodiments, hydrogen gas input 240 shares a port of reaction chamber210 with at least one of conductive powder precursor gas input 220 orinert gas input 230.

RF power unit 245 is configured to ignite the hydrogen gas and the inertgas in order to form a plasma. An RF power applied in the reactionchamber depends on a volume of the reaction chamber. As the volume ofthe reaction chamber increases, the RF power applied in the reactionchamber also increases. In some embodiments, the RF power unit appliesfrom about 10 W to about 300 kW to reaction chamber 210.

Vibration unit 250 is configured to provide vibration to reactionchamber 210. In some embodiments, the vibration unit 250 providesultrasonic vibration to reaction chamber 210. The vibration of reactionchamber 210 helps to reduce an amount of conductive powder or reactionby-products that adhere to sidewalls of reaction chamber 210. In someembodiments, vibration unit 250 includes a transducer on an outersurface of reaction chamber 210. In some embodiments, vibration unit 250includes a gas flowing through a channel or rotating a bearing within achamber.

Cooling section 260 is configured to cool the conductive powder formedby the reaction in reaction chamber 210. In some embodiments, coolingsection 260 exposes the conductive powder to air from an ambientenvironment. In some embodiments, cooling section 260 includes a heatexchanger. In some embodiments, cooling section 260 includes acirculation device configured to circulate a cooling material, e.g.,air, through the conductive powder exiting reaction chamber 210.

Collector 270 is configured to receive the cooled conductive powder fromcooling section 260. Collector 270 is configured to funnel theconductive powder to powder collecting cells 280. In some embodiments,collector 270 includes filters configured to filter the conductivepowder based on particle size. In some embodiments, collector 270 isconfigured to receive a cleaning solution in order to remove reactionby-products from the conductive powder.

Valve 275 is configured to selectively permit the conductive powder topass from collector 270 to powder collecting cells 280. In someembodiments, valve 275 includes a plurality of valves. In someembodiments, each valve of the plurality of valves corresponds to asingle powder collecting cell of powder collecting cells 280. In someembodiments, each valve of the plurality of valves corresponds to agroup of powder collecting cells of powder collecting cells 280. In someembodiments, valve 275 is controlled to permit passage of the conductivepowder in response to a filtering process in collector 270. In someembodiments, valve 275 is controlled to permit passage of the conductivepowder based on a status of powder collecting cells 280, e.g., powdercollecting cells 280 receiving solvent or powder collecting cells 280being full.

Powder collecting cells 280 are configured to receive the conductivepowder and help to separate the conductive powder based on particlesize. In some embodiments, each powder collecting cell of powdercollecting cells 280 is configured to receive particles of theconductive powder having a specific particle diameter range. Forexample, in some embodiments, a first group of powder collecting cellsis configured to receive particles of the conductive powder having adiameter below a threshold value and a second group of powder collectingcells is configured to receive particles of the conductive powder havinga diameter equal to or greater than the threshold value. In someembodiments, powder collecting cells 280 include an ESC to direct theconductive powder into powder collecting cells. In some embodiments,powder collecting cells 280 include a vacuum pump to pull the conductivepowder into powder conductive cells. In some embodiments, powdercollecting cells 280 includes at least one filter. In some embodiments,powder collecting cells 280 includes an agitation device configured tohelp disburse the conductive powder in the solvent.

Valve 285 is configured to permit solvent from solvent inlet 290 toenter powder collecting cells 280. Valve 285 is also configured toselectively permit the conductive powder to pass from powder collectingcells 280 to an output connected to pump 295. In some embodiments, valve285 includes a plurality of valves. In some embodiments, a first valveis connected to solvent inlet 290 and a second valve is connected topump 295. In some embodiments, valve 285 is controlled to permit passageof the conductive powder in response to the conductive powder beingsufficiently disbursed in the solvent. In some embodiments, valve 285 iscontrolled to permit passage of the solvent based on a status of valve275, e.g., valve 275 being closed.

Solvent inlet 290 is configured to provide a solvent from a solventsupply to powder collecting cells 280 through valve 285. The solvent isused to disperse the conductive powder collected in the powdercollecting cells 280. In some embodiments, the solvent includes methane,isopropyl alcohol, acetone, ethyl acetate or another suitable fluid. Insome embodiments, the solvent includes more than one material. In someembodiments, solvent inlet 290 includes multiple inlets, e.g., one foreach material of the solvent.

Pump 295 is configured to remove the conductive powder from powdercollecting cells 280 through valve 285. Pump 295 is capable of removingthe conductive powder dispersed in solvent from solvent inlet 290. Insome embodiments, pump 295 is capable of removing the conductive powderin a non-dispersed state. In some embodiments, pump 295 includes avacuum pump. In some embodiments, pump 295 includes a positivedisplacement pump. In some embodiments, pump 295 is configured totransport the conductive powder, in a dispersed state or non-dispersedstate, to a container for later use.

Controller 297 is configured to control components of device 200.Controller 297 helps device 200 to operate efficiently in order toproduce a conductive powder. Controller 297 is configured to control anopen and closed status of valve 275 and valve 285. In some embodiments,controller 297 is capable of controlling individual valves within valve275 and/or valve 285 independently. Controller 297 is configured tocontrol RF power unit 245 in order to maintain a plasma within reactionchamber 210 during formation of the conductive powder. Controller 297 isconfigured to control pump 295 in order to regulate removal of theconductive powder from powder collecting cells 280. In some embodiments,controller 297 is also configured to control a flow rate of at least oneof conductive powder precursor gas input 220, inert gas input 230,hydrogen gas input 240 or solvent inlet 290. In some embodiments, theflow rates are controlled by controlling valves within the variousinputs and/or inlet. In some embodiments, the flow rate is controlled bycontrolling a pressure in the various inputs and/or inlet. In someembodiments, controller 297 controls vibration unit 250 in order tobegin vibration of reaction chamber 210 when conductive powder isproduced and cease vibration of the reaction chamber when the reactionchamber is not in use. In some embodiments, controller 297 controlstemperature or pressure within reaction chamber 210. In someembodiments, controller 297 controls a heater connected to conductivepowder precursor gas input 220 in order to control a preheat temperatureof the conductive powder precursor gas.

In some embodiments, device 200 is used to implement method 100. In someembodiments, device 200 is used to produce conductive powder in a mannerdifferent from method 100.

FIG. 3 is a flowchart of a method 300 of forming a semiconductor devicein accordance with some embodiments. In operation 302, an opening isformed in the semiconductor device. In some embodiments, the opening isformed using an etching process, e.g., a wet etching or a dry etching.In some embodiments, the opening is formed using a laser drillingprocess or another suitable process. The opening extends through adielectric material and exposes a conductive element or a contact regionof a component of the semiconductor device. In some embodiments, thedielectric material is silicon oxide, silicon nitride, siliconoxynitride or another suitable dielectric material. A meltingtemperature of the dielectric material is greater than a meltingtemperature of a conductive powder used to fill the opening in thedielectric material.

In operation 304, the opening is lined with a catalyst layer. In someembodiments, the catalyst layer includes cobalt, nickel, titanium oranother suitable catalyst material. In some embodiments, the catalystlayer is formed using chemical vapor deposition (CVD), physical vapordeposition (PVD), atomic layer deposition (ALD), plating or anothersuitable formation process.

In operation 306, a graphene layer is formed over the catalyst layer. Insome embodiments, the graphene is formed using CVD, PVD or anothersuitable formation method. In some embodiments, a thickness of thegraphene ranges from about 5 nm to about 100 nm.

In operation 308, a remaining portion of the opening is filled with aconductive powder dispersed in a fluid. In some embodiments, theconductive powder is suspended in the fluid by vibrating. The fluidcontaining the suspended conductive powder is spread, e.g., by spincoating, the fluid upon wafer to fill in the opening. In someembodiments, the conductive powder is dispersed in a solvent. Theremaining portion of the opening is filled by flowing the fluidcontaining the dispersed conductive powder over the semiconductordevice. The fluid will flow into the opening and carry the conductivepowder into the opening. In some embodiments, an average size of theparticles of the conductive powder is less than 10 nm. In someembodiments, an average size of the particles of the conductive powderranges from about 1 nm to about 5 μm. As a particle size increases,filling the opening becomes more difficult, in some instances. As aparticle size decreases, a risk of the particles of the conductivepowder failing to fill the opening increases, in some instances.

In operation 310, the fluid is evaporated. Evaporating the fluid removesthe fluid from the opening and leaves behind only the conductive powderover the graphene layer. In some embodiments, the fluid is evaporatedusing heat. In some embodiments, the fluid is evaporated by reducing apressure above the semiconductor device.

In operation 312, the conductive powder is melted. Melting theconductive powder helps to form a uniform distribution of conductivematerial in the opening in order to help ensure electrical connection toan element exposed by the opening. In some embodiments, the conductivepowder is melted using an anneal process. In some embodiments, theanneal process is a laser anneal process. In some embodiments, the laseris a continuous wave (CW) laser. The laser is scanned over a surface ofthe semiconductor device and melts the conductive powder exposed to theradiation from the laser. In some embodiments, the laser is scanned overthe surface of the semiconductor device by using optical elements tochange a direction of the laser with respect to the semiconductordevice. In some embodiments, the laser remains stationary and thesemiconductor device is moved with respect to the laser, for exampleusing a stepper motor. In some embodiments, both the laser and thesemiconductor device are moved either sequentially or simultaneously. Insome embodiments, the laser is scanned over the semiconductor device ina two-dimensional scan. In some embodiments, the laser is scanned overthe semiconductor device in a one-dimensional scan.

In some embodiments, a speed of the laser scan across the surface of thesemiconductor device ranges from about 10 cm/min to about 30 cm/min. Asa speed of the laser scan increases, a risk of incomplete melting of theconductive powder increases, in some instances. As the speed of thelaser scan decreases, a risk of damage to other components in thesemiconductor device increases, in some instances. In some embodiments,a width of the laser contacting the semiconductor device in a scanningdirection ranges from about 0.3 cm to about 0.5 cm. As a width of thelaser increases, precision in the control of the laser is reduced, insome instances. As the width of the laser decreases, a production timefor the semiconductor device increases, in some instances. In someembodiments, a width of the laser contacting the semiconductor device ina direction perpendicular to the scanning direction ranges from about 4cm to about 6 cm. As a width of the laser increases, precision in thecontrol of the laser is reduced, in some instances. As the width of thelaser decreases, a production time for the semiconductor deviceincreases, in some instances.

In operation 314, the semiconductor device is planarized. Planarizingthe semiconductor device removes a portion of the melted conductivepowder outside of the opening. Also, a portion of the graphene layer andthe catalyst layer outside the opening are removed by planarizing thesemiconductor device. In some embodiments, a chemical mechanicalpolishing (CMP) process is used to planarize the semiconductor device.In some embodiments, a grinding process, an etching process or anothersuitable process is used to planarize the semiconductor device.

Method 300 is able to fill an opening having a smaller dimension thanother processes. For example, method 300 is able to fill openings for 10nm technology nodes and lower because the particles size of theconductive powder is small and the conductive powder is dispersed in thefluid, which helps to move the conductive powder into the opening. Acarbon content of the conductive material formed using method 300 isalso reduced in comparison with other approaches. For example, aconductive line formed by electro copper plating (ECP) has a carboncontent greater than 50 parts per million (ppm). In contrast, aconductive line formed by method 300 has a carbon content less than 50ppm, in some instances. Carbon will increase the resistance of theconductive line above the resistance of pure copper. The increase inresistance increases heat generated by operating the semiconductordevice, slows signal transfer and reduces precision of signal transfer.Reducing the carbon content in the conductive line helps to form asemiconductor device which will operate as designed and produce lessheat in comparison with a semiconductor device having a higher carboncontent in the conductive lines.

In some embodiments, at least two operations of method 300 are performedsimultaneously. For example, in some embodiments operation 310 isperformed simultaneously with operation 312. In some embodiments, atleast one operation of method 300 is omitted. For example, in someembodiments, operation 314 is omitted.

FIG. 4A is a cross-sectional view of a semiconductor device 400following formation of a graphene layer in openings in accordance withsome embodiments. In some embodiments, semiconductor device 400 is asemiconductor device after operation 306 of method 300 (FIG. 3).Semiconductor device 400 includes a substrate 402. A plurality ofisolation features 404 are in substrate 402. A plurality of transistors410 are on substrate 402. Each transistor 410 includes a channel region420 in substrate 402 between a source region 422 a and a drain region422 b. A gate contact 412 extends from a gate of one of the transistor410 and is electrically connected to the gate. A source contact 424 aextends from source region 422 a and is electrically connected to thesource. A drain contact 424 b extends from drain region 422 b and iselectrically connected to the drain. An inter-layer dielectric (ILD) 430is over substrate 402. Gate contact 412, source contact 424 a and draincontact 424 b extend through ILD 430. A dielectric layer 440, e.g., aninter-metal dielectric (IMD) layer, is over ILD 430. A plurality ofopenings 450 are in dielectric layer 440. A catalyst layer 442 linesdielectric layer 440 including sidewalls and bottom surfaces of openings450. A graphene layer 444 is over catalyst layer 442.

One of ordinary skill in the art would recognize that a gate contactwould also be formed for more than one transistor 410, in someembodiments. Additionally, source/drain contacts would also be formedfor more than one transistor 410, in some embodiments. The arrangementof semiconductor device 400 omits some features, such as additional gatecontacts and source/drain contacts, for the sake of clarity.

Openings 450 are formed in a metal layer directly over a layercontaining contacts, e.g., gate contact 412, source contact 424 a anddrain contact 424 b. In some embodiments, the metal layer formed indielectric layer 440 is called metal layer 1 or M1. In some embodiments,openings 450 are formed in ILD 430 and expose a gate or source/drainregions of a transistor. In some embodiments, the metal layer formed inILD 430 is called metal layer 0 or M0. In some embodiments, openings 450are in a metal layer farther from substrate 402 than M1.

FIG. 4B is a cross-sectional view of a semiconductor device 400′following formation filling openings with a conductive powder inaccordance with some embodiments. In some embodiments, semiconductordevice 400′ is a structure following operation 308 of method 300 (FIG.3). Semiconductor device 400′ is similar to semiconductor device 400 andsame reference numbers refer to same elements. In comparison withsemiconductor device 400, semiconductor device 400′ includes conductivepowder 460 in openings 450. In some embodiments, conductive powder 460is dispersed in a fluid. In some embodiments, conductive powder 460 isin a non-dispersed state. In some embodiments, the conductive powderincludes aluminum, cobalt, copper, gold, magnesium, nickel, silver,titanium, zinc, alloys thereof or other suitable material.

FIG. 4C is a cross-sectional view of a semiconductor device 400″following formation melting of conductive powder in accordance with someembodiments. In some embodiments, semiconductor device 400″ is astructure following operation 312 of method 300 (FIG. 3). Semiconductordevice 400″ is similar to semiconductor device 400′ and same referencenumbers refer to same elements. In comparison with semiconductor device400′, semiconductor device 400″ includes a conductive material 470 inopenings 450. Conductive material 470 includes a same material asconductive powder 460. In comparison with conductive powder 460,conductive material 470 includes fewer interfaces. Conductive material470 is formed by melting conductive powder 460, e.g., by a laserannealing process.

FIG. 4D is a cross-sectional view of a semiconductor device 400*following a planarization process in accordance with some embodiments.In some embodiments, semiconductor device 400* is a structure followingoperation 314 of method 300 (FIG. 3). Semiconductor device 400* issimilar to semiconductor device 400″ and same reference numbers refer tosame elements. In comparison with semiconductor device 400″,semiconductor device 400* includes a top surface of dielectric layer 440exposed. A planarization process, e.g., CMP, was used to remove catalystlayer 442, graphene layer 444 and conductive material 470 outside ofopenings 450. The planarization process produces a top surface ofdielectric layer 440 which is substantially coplanar with a top surfaceof conductive material 470.

A carbon content of conductive material 470 is less than 50 ppm. The lowcarbon content of conductive material 470 helps to maintain a lowresistance of conductive material 470 in comparison with other devices.

FIG. 5 is a schematic view of a controller 500 for controlling a devicefor forming a conductive powder in accordance with some embodiments.Controller 500 includes a hardware processor 502 and a non-transitory,computer readable storage medium 504 encoded with, i.e., storing, thecomputer program code 506, i.e., a set of executable instructions.Computer readable storage medium 504 is also encoded with instructions507 for interfacing with manufacturing machines for producing theconductive powder. The processor 502 is electrically coupled to thecomputer readable storage medium 504 via a bus 508. The processor 502 isalso electrically coupled to an I/O interface 510 by bus 508. A networkinterface 512 is also electrically connected to the processor 502 viabus 508. Network interface 512 is connected to a network 514, so thatprocessor 502 and computer readable storage medium 504 are capable ofconnecting to external elements via network 514. The processor 502 isconfigured to execute the computer program code 506 encoded in thecomputer readable storage medium 504 in order to cause controller 500 tobe usable for performing a portion or all of the operations as describedin method 100.

In some embodiments, the processor 502 is a central processing unit(CPU), a multi-processor, a distributed processing system, anapplication specific integrated circuit (ASIC), and/or a suitableprocessing unit.

In some embodiments, the computer readable storage medium 504 is anelectronic, magnetic, optical, electromagnetic, infrared, and/or asemiconductor system (or apparatus or device). For example, the computerreadable storage medium 504 includes a semiconductor or solid-statememory, a magnetic tape, a removable computer diskette, a random accessmemory (RAM), a read-only memory (ROM), a rigid magnetic disk, and/or anoptical disk. In some embodiments using optical disks, the computerreadable storage medium 504 includes a compact disk-read only memory(CD-ROM), a compact disk-read/write (CD-R/W), and/or a digital videodisc (DVD).

In some embodiments, the storage medium 504 stores the computer programcode 506 configured to cause controller 500 to perform method 100. Insome embodiments, the storage medium 504 also stores information neededfor performing a method 100 as well as information generated duringperforming the method 100, such as a solvent flow rate parameter 516, aprecursor flow rate parameter 518 for monitoring a flow rate of aconductive powder precursor gas flow rate, an inert gas flow rateparameter 520, hydrogen gas flow rate parameter 522 and/or a set ofexecutable instructions to perform the operation of method 100.

In some embodiments, the storage medium 504 stores instructions 507 forinterfacing with manufacturing machines. The instructions 507 enableprocessor 502 to generate manufacturing instructions readable by themanufacturing machines to effectively implement method 100 during amanufacturing process.

Controller 500 includes I/O interface 510. I/O interface 510 is coupledto external circuitry. In some embodiments, I/O interface 510 includes akeyboard, keypad, mouse, trackball, trackpad, and/or cursor directionkeys for communicating information and commands to processor 502.

Controller 500 also includes network interface 512 coupled to theprocessor 502. Network interface 512 allows controller 500 tocommunicate with network 514, to which one or more other computersystems are connected. Network interface 512 includes wireless networkinterfaces such as BLUETOOTH, WIFI, WIMAX, GPRS, or WCDMA; or wirednetwork interface such as ETHERNET, USB, or IEEE-1394. In someembodiments, method 100 is implemented in two or more controllers 500,and information such as memory type, memory array layout, I/O voltage,I/O pin location and charge pump are exchanged between differentcontrollers 500 via network 514.

The above description includes some embodiments for forming a conductivepowder having sufficiently small particle size to fill openings for 10nm technology nodes and smaller. The conductive powder is able toeffectively fill openings for conductive lines or vias in asemiconductor device to increase reliability of the semiconductor deviceand production yield.

One aspect of this description relates to a method of forming aconductive powder. The method includes reducing, by a reductionreaction, a conductive powder precursor gas using a plasma. Reducing theconductive powder precursor gas forms the conductive powder. The methodfurther includes filtering the conductive powder based on particle size.The method further includes dispersing a portion of the conductivepowder having a particle size below a threshold value in a fluid.

Another aspect of this description relates to a device for forming aconductive powder. The device includes a reaction chamber configured toreceive a conductive powder precursor gas, an inert gas and a hydrogengas. The device further includes a radio frequency (RF) power unitconfigured to ignite a plasma using the inert gas and the hydrogen gas.The plasma is usable to reduce, by a reduction reaction, the conductivepowder precursor gas to form the conductive powder. The device furtherincludes powder collecting cells configured to separate the conductivepowder based on particle size. The device further includes a solventinlet configured to provide a solvent to the powder collecting cells fordispersing the conductive powder in a solvent.

Still another aspect of this description relates to a method of forminga semiconductor device. The method includes forming at least one openingin a dielectric material. The method further includes depositing agraphene layer in the at least one opening. The method further includesfilling the at least one opening with a conductive powder dispersed in afluid. The method further includes melting the conductive powder.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method of forming a conductive powder, themethod comprising: reducing, by a reduction reaction, a conductivepowder precursor gas using a plasma to form the conductive powder;filtering the conductive powder based on particle size; and dispersing aportion of the conductive powder having a particle size below athreshold value in a fluid.
 2. The method of claim 1, further comprisingpreheating the conductive powder precursor gas prior to the reducing ofthe conductive powder precursor gas.
 3. The method of claim 1, furthercomprising performing an ultrasonic vibration on a reaction chambersimultaneously with the reducing of the conductive powder precursor gasin the reaction chamber.
 4. The method of claim 1, wherein the filteringof the conductive powder comprises performing at least one of anelectro-static collector (ESC) process or a centrifugal process.
 5. Themethod of claim 1, wherein the dispersing of the conductive powder inthe fluid comprises dispersing the conductive powder in a fluid free ofoxygen.
 6. The method of claim 1, wherein the dispersing of theconductive powder in the fluid comprises dispersing the conductivepowder in a solvent including methane, acetone or isopropyl alcohol. 7.The method of claim 1, wherein the reducing of the conductive powderprecursor gas comprises reducing the conductive powder precursor gascomprising a conductive-material organic compound.
 8. The method ofclaim 1, wherein the reducing of the conductive powder precursor gascomprises reducing the conductive powder precursor gas comprising aconductive-material halide compound.
 9. The method of claim 1, whereinthe reducing of the conductive powder precursor gas comprises reducingthe conductive powder precursor gas in a reaction chamber at a pressureranging from about 10 milliTorr (mTorr) to about 20 Torr, at a radiofrequency (RF) power ranging from about 10 watts (W) to about 300kilowatts (kW), and at a temperature ranging from about 100° C. to about600° C.
 10. A device for forming a conductive powder, the devicecomprising: a reaction chamber configured to receive a conductive powderprecursor gas, an inert gas and a hydrogen gas; a radio frequency (RF)power unit configured to ignite a plasma using the inert gas and thehydrogen gas, wherein the plasma is usable to reduce, by a reductionreaction, the conductive powder precursor gas to form the conductivepowder; powder collecting cells configured to separate the conductivepowder based on particle size; and a solvent inlet configured to providea solvent to the powder collecting cells for dispersing the conductivepowder in a solvent.
 11. The device of claim 10, further comprising avibration unit configured to vibrate the reaction chamber duringreduction of the conductive powder precursor gas.
 12. The device ofclaim 10, further comprising a valve configured to regulate a flow ofthe solvent from the solvent inlet to the powder collecting cells. 13.The device of claim 10, further comprising a pump for removing theconductive powder dispersed in the solvent from the powder collectingcells.
 14. A method of forming a semiconductor device, the methodcomprising: forming at least one opening in a dielectric material;depositing a graphene layer in the at least one opening; filling the atleast one opening with a conductive powder dispersed in a fluid; andmelting the conductive powder.
 15. The method of claim 14, wherein themelting of the conductive powder comprises melting the conductive powderusing a laser anneal process.
 16. The method of claim 15, wherein thelaser anneal process comprises scanning a laser over a surface of thesemiconductor device.
 17. The method of claim 14, further comprisingplanarizing the semiconductor device.
 18. The method of claim 14,further comprising evaporating the fluid.
 19. The method of claim 18,wherein the evaporating of the fluid comprises evaporating the fluidprior to melting the conductive powder.
 20. The method of claim 14,further comprising lining the at least one opening with a catalystlayer, wherein the graphene layer is deposited on the catalyst layer.